Access to computer networks has become a ubiquitous part of today's computer usage. Whether accessing a Local Area Network (LAN) in an enterprise environment to access shared network resources, or accessing the Internet via the LAN or other access point, it seems users are always logged on to at least one service that is accessed via a computer network. Moreover, the rapid expansion of cloud-based services has lead to even further usage of computer networks, and these services are forecast to become ever-more prevalent.
Expansion of network usage, particularly via cloud-based services, as been facilitated via substantial increases in network bandwidths and processor capabilities. For example, broadband network backbones typically support bandwidths of 10 Gigabits per second (Gbps) or more, while the standard for today's personal computers is a network interface designed to support a 1 Gbps Ethernet link. On the processor side, processors capabilities have been increased through both faster clock rates and use of more than one processor core. For instance, today's PCs typically employ a dual-core processor or a quad-core processor, while servers may employ processors with even more cores. For some classes of servers, it is common to employ multiple processors to enhance performance. In addition, it is envisioned that much if not most of the future processor performance increases will result from architectures employing greater numbers of cores, and that future servers may employ greater numbers of processors.
One of the primary considerations in data center implementations is power consumption. In addition to the financial cost of power, a significant aspect of data center power consumption relates to cooling. Under a typical data center design, multiple high-density server racks are arrayed in rows, with each server rack comprising multiple blade servers, each with its own set of server blades. In other configurations, server racks may house multiple stand-alone servers, such a 1 U, 2 U and 4 U rack-mounted servers. In the case of server blades, each blade typically has one or more multi-core processors and its own memory and networking resources.
Generally, the workload supported by a data center will vary throughout a day, with higher workloads present during normal working hours, with lower workloads during nights and weekends. In order to support such variable workloads, data centers are configuration to be dynamically scaled. Recent advances in processor and system architectures enable computer systems such as server blades and stand-alone servers to be put into lower-power idle states or sleep states. This is the preferred scheme for temporarily taking server resources offline rather than shutting servers down. The amount of power consumption when in an idle or sleep state is relatively low, particularly when put in a deep sleep state (e.g., a hibernation mode or standby mode).
Modern servers often are configured with a baseboard management controller (BMC) or the like. A BMC can be accessed via a remote management facility over a computer network, enabling remote management of an individual server or set of servers (e.g., a BMC in a management board in a blade server rack). In order to support BMC availability, network communications need to be enabled, including while a server is operating in a lower power state. Power for a network controller or the like is typically provided from a system or rack power supply, either as a normal power signal or an auxiliary power signal. Currently, 10 Gigabit Ethernet (GbE) network adaptor power requirements may exceed the standby power level supplied by some standard bus/interconnects, such as available via Peripheral Component Interconnect Express (PCIe) buses. Therefore, 10 GbE network adapters have required use of a separate auxiliary power supply when their host systems are operating in reduced power states.